This application proposes the continuation of a family study of sexual orientation and related behaviors. Samples of homosexual and heterosexual men will be recruited for testing and interview and their siblings will also be recruited for participation. The hypothesis being tested is that homosexual subjects have more homosexual siblings than do heterosexual subjects. In addition, measures of cognitive abilities and "masculinity-femininity" will be taken and lifetime history of mental disorder will be determined by interview both in index subjects and their family members. The purpose is to see whether homosexuals and heterosexuals differ on personality dimensions other than sexual object choice. This project will provide key information about the familiar nature of sexual orientation and about possibly related personality traits. The results may provide the basis for genetic, hormonal or longitudinal development studies to elucidate the origins of sexual orientation.